Vladimir Putin, now in his fourth and perhaps final term as Russia's president, faced a key political test in regional elections Sept. 9. And though his ruling party, United Russia, won most of the races - which included gubernatorial elections in 22 regions, legislative elections in 16 regions and a mayoral election in Moscow - it faced stiffer competition and more unrest than usual.

In a record four regions, the ruling party's gubernatorial candidates failed to obtain a simple majority of the ballots and will stand in runoff elections Sept. 23. Their opponents are candidates from the Communist and Liberal Democratic parties, registered political parties that work within Russia's political system and don't pose a strong threat to Putin's government. Even so, the result is troubling for the ruling party and practically unprecedented in Russia: Only once before has a gubernatorial race gone to a runoff since Putin reinstated direct regional elections in 2012. (United Russia lost that vote, in Irkutsk, to the Communist Party.)

The main force behind United Russia's comparatively lackluster performance in the polls is the Kremlin's plan to increase the retirement age. The reform is part of the government's effort to steel Russia's finances against sanctions from the West and to cope with the country's aging and shrinking population. But it is wildly unpopular among Russians, many of whom expressed their discontent at the ballot box. Three of the four regions that will hold runoff votes are in Siberia, where the population is older on average than in the European part of Russia. Opposition candidates in each of these races campaigned against the new retirement age. Pension reform also fueled protests across Russia on election day. Instead of heading to the polls, thousands of people in more than 30 cities turned out for demonstrations organized by opposition leader Alexei Navalny. (He remains under house arrest and could not join the protesters.) The protests drove voter participation down to about 30 percent, further detracting from United Russia's wins.

The protests and the results of the election demonstrate that while Putin and the ruling party still have tight control over Russia's political system, they are not impervious to dissent. As Putin tries to stabilize the country's finances, ravaged by years of recession, he will also have to factor in shorter-term political considerations. Before the regional votes, in fact, the president announced plans to amend the pension reform in an effort to appease voters. Further adjustments may be necessary for Putin to stem the growing unrest in Russia, but they will come at a cost for the Kremlin.